To compare the influence of different doses of sufentanil administrated intraperitoneally on anesthesia and recovery in rats,sixty adult SD rats are randomly divided into 5 groups(S1～S5).Rats in S1～S5 are given a single intraperitoneal injection of sufentanil 50,60,150,250 and 400 μg/kg body weight respectively.The loss of righting reflex(LRR),the duration of post-LRR ataxia and the grip time in the duration of the post-LRR ataxia are recorded,and the anesthesia depth is assessed.The data of statistics analysis show that LRR rate in S2～S5 are 100%,whereas in S1 is 83.3%.With the increase of dose administrated,the time for induction of LRR decreased,the depth of anesthesia increased,the duration of LRR and post-LRR ataxia are prolonged and the time of grip is reduced.The results demonstrate that the effect of sufentanil administrated intraperitoneally on anesthesia and recovery in rats presents dose-dependence,and sufentanil in the dose of 60～150 μg/kg provides optimal depth of anesthesia and recovery quality.